We think a lot about how plant-based diets and animal-based affect our hearts, our blood sugar levels, or our risk for cancer, but how do our dietary choices affect our brains? What do we actually know about vegan diets and mental health? As a psychiatrist who specializes in nutrition, this question is near and dear to my heart, and one that richly deserves our attention.
Those of you familiar with my work know that I eat a highly unorthodox mostly-meat, low-plant diet, but that was not always the case. In my 20s and 30s I ate a low-meat, low-fat, high-plant diet because that’s what I was told was best for me.
In my early 40s, numerous mysterious symptoms descended upon me—chronic fatigue, fibromyalgia, IBS, migraines, etc.—forcing me to experiment with my diet in hopes of finding relief. The diet that completely resolved all of those issues and more, was a high cholesterol, high-fat, low-fiber diet. Naturally, I was worried that this strange new diet would slam my arteries shut, so I began to study the science behind the headlines.
We are all doing our best with the information we have to make healthy choices. It’s just that the information we have can be really confusing and is often divisive. I’d like to challenge some assumptions on both sides of the great plant vs. animal diet debate that are often overlooked, in hopes of finding common ground and creating a foundation for meaningful dialogue.
Yes, I will be making the case for meat (red meat, poultry, and/or seafood), and no, I am not funded by the meat industry. My sincere intention is to support everyone in making their diet of choice healthier by providing useful information.
My reading of nutrition science over the past ten years has led me to conclude that vegan diets are hard on the human body… but I will argue below that omnivorous diets can be hard on the body, too.
Vegan diets contain no animal foods whatsoever, and are therefore naturally cholesterol-free and typically low in saturated fat. An ever-growing number of influential individuals and powerful institutions actively promote diets rich in plant foods and low in animal foods—from health care professionals like physicians and dietitians to government agencies like the USDA and the World Health Organization. No wonder more and more consumers believe a vegan diet is the holy grail of human health.
This, despite the undisputed fact that un-supplemented vegan diets are nutritionally incomplete.
This alone should give one pause about the merits of vegan diets. Even with supplementation, it is challenging for people who choose plant-based diets to meet their nutritional requirements using strictly whole foods. In fact, even though the plant-rich diet recommended by the USDA allows some animal foods, it is so nutritionally weak that the US Dietary Guidelines specifically recommend that EVERYONE eats refined carbohydrates like flour and cereals, because they are fortified with essential nutrients:
“Refined grains, such as white flour and products made with white flour, white rice, and de-germed cornmeal, are part of the intake recommendation because they are commonly enriched with iron and several B vitamins, including thiamin, niacin, and riboflavin…
"Since 1998, enriched grains also have been fortified with folic acid and are thus an important source of folic acid for women of childbearing potential…The 2015 DGAC concluded that consumption of only whole grains with no replacement or substitution would result in nutrient shortfalls.” [Part D, chapter 1, lines 1088-1156]
The USDA recommends that grains and legumes serve as staple protein foods, despite the awkward fact that those foods are such poor sources of vital nutrients that they need to be artificially fortified…and you can’t fortify a whole food. [Dairy is arguably an exception, but we’ll get to dairy further below…and vegan diets exclude dairy products].
In contrast, red meat, poultry and seafood are naturally nutritionally dense and have been part of the human diet for nearly two million years–why not specifically recommend these as staple sources of protein?.
The short answer? Un-supplemented vegan diets lack key nutrients required for human cells to operate, and therefore are incompatible with human life. Of course they will cause brain malfunction, but exactly what that will look like in different individuals is hard to predict.
In my next post, Your Brain On Plants, I delve into the details of how plant-based and animal-based diets compare in terms of vitamins, minerals, protein, cholesterol, and essential fatty acids—and how those differences affect the brain and various psychiatric conditions. Even I was surprised to learn some of the things that came to light as I worked on that article.
Spoiler alert: there is strong, irrefutable scientific evidence that un-supplemented and improperly-supplemented vegan diets jeopardize overall mental health.
One of the most concerning things I learned in my research is that most vegans are not properly assessed for critical deficiencies and most do not supplement correctly. Whether carefully supplemented vegan diets can sustain excellent mental health is a different question altogether. I honestly don’t think anyone knows the answer. Vegan diets are a relatively new phenomenon in world history. Completely removing animal foods from the diet is a risky human experiment—although, to be fair, so is eating the standard American diet…
Every person’s diet is different, every person’s system is unique, and there are many factors to consider when evaluating the health of any given diet. I am convinced that including some animal protein and fat in the diet is very important, but many will disagree.
Even if I could convince everyone of the importance of animal foods to human health, I’m sure some would continue to exclude them from their diets for other important personal reasons.
My reading of the evidence is that removing refined carbohydrates and processed foods is what makes plant-based diets appear healthier in clinical studies, so regardless of what you choose to keep IN your diet, make sure you get the junk OUT.